Circuit-closer



(No Model.)

W. C. JOHNSTON, Jr. CIRCUIT GLUSBR.

No. 450,292. Patented Apr. 14, 1891.

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UNITED STATES PATENT OFFICE.

WUJAM C. JOHNSTON, JR., OF LYNN, MASSACHUSETTS.

ClRCUlT-CLOSER.

SPECIFICATION forming part of Letters Patent No. 450,292, dated April14, 1891.

Application led December 17, 1888. Renewed February 3, 1891. Serial No.379,977. (No model.)

To @ZZ whom, z't may concern;

Be it known that I, .VILLIAM C. JOHNSTON, Jr., of Lynn, in the county ofEssex and Commonwealth of Massachusetts, have invented an ImprovedDevice o`r Means for Making-and Breaking. Electric Circuits, of whichthe following, taken in connection with the accompanying drawings, is aspecification.

This invention has for its object mainly to provide a device for makingand breaking' electric circuits, which shall be positive inits operationand not liable to be disturbed by foreign matter or particles ofcorroding metal interposed between the contact-surfaces.

To this end the invention consists in the combination, in an electriccircuit, of two contact Surfaces or terminals arranged so as to bebrought together and separated by a movement which causes theccntactsurfaces to slide over eachother, whereby foreign matter andcorroding particles are removed and the contact-surfaces kept polished.

In the drawings, Figure 1 is au elevation of a central cross-section ofthe device embodying my invention and represents the circuit opened, thecontactsurfaces being drawn apart. Fig. 2 is a similar view representingthe contact-surfaces together, the circuit being in this case closed.Fig. 3 is a perspective view representing the device, the casing orshell being opened to illustrate the mechanism within.

The device represented in the drawings is designed for combination withan electric cable. To that end itis provided with a central opening orhole for receiving the cable.

The device is preferably formed in two parts in order to facilitate thecombination thereof with the cable. The one part A is provided with theterminals c c. Said terminals are connected with the supporting-shell Aby means of suitable connections, as screws b. They are preferablycomposed of spring metal and formed substantially as represented. Saidterminals are connected with the electric conductor, so that the currentis made to pass through said terminals when the same are closed togetherand is interrupted or opened when the terminals arc drawn apart. Thepart B of the casing` is provided with a suitable opening in which islocated a plunger f, the bottom end of which bears upon the terminal eand the opposite end of which reaches outward through the shell, asrepresented. A suitable inward pressure applied by the thumb or thelinger of the operator to said plunger forces downward the terminal e,whereby the said terminal is first made to contact with the terminal c,and next by a further movement to slide or move its own contact-surfaceover the adjacent surface of the terminal c, to facilitate whichoperation the terminals are preferably formed of spring metal, so as toyield to accommodate each other. Then pressure is removed from saidplunger f, it is forced out.- ward by the tension of springterminal e,which litts to its normal position away from the terminal u, as shown inFig. 1. The plunger f is represented as covered by a hood-.71., formedof rubber or other iiexible material, which serves to keep dust fromentering the casing and yields to permit operation of the plunger, asdescribed.

A device formed as described is kept polished and in condition foropera-tion by the movement of the contact-surfaces consequent upon theclosing of the circuit, substantially as described.

I claim- In combination, the casing, the stationary contact a, having aturned-up end, the movable contact c, ot' spring material, curvingupwardly and extending over and above the edge of the contact a andnormally out ot contact with the same, and the push-button to bear uponthe curved spring-contact e to cause the saine to bear upon the edge ofthe contact a and slide thereon, substantially as described.

Signed at Boston, Massachusetts, this 21st day of November, A. D. 1388.

TILLIAM C. JOHNSTON, JR.

Witnesses:

E. E. HAMILL, (I. l. lu'rirnn

